Police launched dawn raids on about 190 mosques, flats and offices linked to an Islamist group in Germany on Tuesday as the government banned the organisation, accusing it of radicalising youngsters, the interior ministry said.

Interior Minister Thomas de Maiziere said the DWR 'True Religion' organisation had contacted young people as it distributed copies of the Holy Quran and other religious material, and had persuaded about 140 of them to join militants in Iraq and Syria.

DWR made no reference to the raids on its website and did not immediately respond to a request for comment.

German Chancellor Angela Merkel has faced pressure to harden her line on security after a string of attacks claimed by Islamic State across Europe and criticism of her decision to let in about 900,000 migrants last year.

"Today's ban is not directed against the distribution of the Quran or translations of the Quran," de Maiziere told reporters. He added, "Today's ban is rather directed against the abuse of religion by people propagating extremist ideologies and supporting terrorist organisations under the pretext of Islam."

The group had several hundred members, he said.

Concern over the number of migrants entering the country has boosted support for Alternative for Germany, a populist party that says Islam is incompatible with the German constitution and has siphoned off support from Merkel's conservatives.

A spokeswoman for the interior ministry said there was no indication that DWR was planning attacks itself.

The ban means DWR is now prohibited from taking part in information and distribution campaigns. De Maiziere said Tuesday's actions across 10 German states were the biggest crackdown on a group since the government shut down a movement known as Kalifatstaat (Caliphate State) in 2001, accusing it of "extremist activities".

The government has also banned five other organisation accused of having Islamist-Jihadist aspirations since 2012.